It is proposed to continue work on our in vitro system obtained from shrimp muscle which is capable of synthesizing homarine from 2-C14-glycine. Since picolinic acid appears not to be a significant intermediate in the biosynthesis, we intend to look for substances related to picolinic acid which may be involved. Quinolinic acid is also not formed from glycine. 2-C14-acetate is converted in this system to quinolinic acid which is subsequently methylated to form N-methyl quinolinic acid. Quinolinic acid is therefore not converted to homarine as previously reported. The two N-methyl substances are very similar chemically and chromatographically, and are difficult to separate. A second metabolic pathway will accordingly be investigated -- the biosynthesis of quinolinic acid from acetate. BIBLIOGRAPHIC REFERENCES: Hall, E.R. and Gurin, S. Experiments in Marine Biochemistry - Homarine Metabolism in Penaeus duorarum. J. of Biol. Chem. 250(17):6943-6946. 1976.